1. Field of the Invention
The present invention relates to a flame device and, particularly, to a flame device producing a stable and elongated swirling flame.
2. Description of the Related Art
U.S. Pat. No. 7,097,448 discloses a vortex type gas lamp for producing an upwardly directed vortex flame inside a surrounding and confined boundary of a rotating body of air. An interface is located between the body of air which is devoid of gas and a central region of gas which is bounded by the interface during the operation of the gas lamp. All of the combustion of gas substantially occurs inside the interface. The gas lamp has a central axis and includes a base supplying combustible gas without air at and nearly adjacent to the central axis. The gas lamp further includes a shield including first and second axially extending sections structurally attached to the base in a fluid sealing relationship. The first and second sections are substantially identical and transparent to light, and each includes an impermeable wall having an arcuate inner surface and an arcuate outer surface. Furthermore, each of the first and second sections has first and second edges extended axially. The gas lamp yet further includes the first and second walls alternately overlapping one another. The first and second walls are adjacent to their edges and are spaced from one another to form tangentially directed ports, thereby forming an axially extending mixing chamber open at its side only through the ports. Furthermore, the first and second sections are arranged so that at the base they surround the entry of the combustible gas and so that the gas receives air for combustion only through the ports. Thus, combustion of the gas results in a flame spaced from the inner surfaces, and the peripheral body of air is devoid of gas entering through the ports. Generally, if no air is supplied for combustion, a flame will extinguish. Unfortunately, it is not easy to prevent excess air from entering the chamber through the ports and to create a stable swirling flame during combustion, since the ports are directly open to air. If the device is placed under an environment with wind, a height and swirling pattern of the flame can be greatly disturbed by excess air flow through the ports caused by wind. Additionally, the base of the chamber is also heated during combustion, but there is not enough air flow through the base to provide cooling and to cause the top surface of the base to be very hot and not safe to touch.
Furthermore, U.S. Design Pat. No. 621,873 discloses a fire tornado lamp including a base and a shield. The base includes a plurality of ports disposed circumferentially. The shield is transparent to light, is hollow and includes a passage extended therein. The base and the shield are connected to each other. Each port extends radially with respect to and is in communication with the passage defined in the shield. Each port is so configured that it induces air into the passage in a direction substantially tangential to a circumference of the passage. Likewise, it is not easy to preclude excess air from entering through the ports, and the flame is susceptible to wind. Also, the guided air flow provided for combustion and cooling can only enter the chamber through the ports above the bottom of the burning flame at an angle perpendicular to the flame direction. This configuration can generate a swift swirling flame and can induce strong convection during combustion. However, it is difficult to control the swirling speed and pattern of the flame, and the base of the device can be very hot.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.